Air separation unit cold box maintenance

When the air separation unit is in normal operation, the liquid flows down and can only flow on the tray and flow to the lower tray through the overflow bucket because the supporting force of the rising steam prevents the liquid from flowing down from the small hole of the tray. After shutdown, due to the interruption of rising gas flow, the liquid on the tray can flow from the overflow bucket to the lower tray, and also can flow through the small hole on the tray to the lower tray. This will cause the surface of liquid oxygen and liquid air rise, which may exceed the position of the expansion air outlet pipe, resulting in liquid carrying accident of the expander during restart. Therefore, pay attention to the liquid level position when stopping.

1. Before connecting the pipe orifice of each container, clean white cloth shall be used to tie the orifice to prevent grease and dirt from entering. 2. When welding in the cold box and in the condensing evaporator, it is strictly forbidden for flame or arc to touch the surface of vessels and pipes. 3. The containers, valves, pipes and corresponding supports in the cold box, the surface of the cold box and the foundation surface shall not be stained with grease after installation, otherwise, degreasing treatment shall be carried out.